THE BLOG

The 'Cold' Facts About Zinc

12/12/2012 01:33 pm ET | Updated Feb 11, 2013

It's cold season again, the time of year when school hallways, office cubicles and airplanes echo with the sound of coughs, sneezes and sniffles. Cold symptoms typically last about seven days and most would do anything to lessen the suffering. Enter the essential mineral zinc, which may stop colds cold, but the key is delivering the right type of zinc at the right time.

Most colds are caused by rhinoviruses, a family of 99 viruses that trigger the hallmarks of suffering like sore throat, runny nose, nasal congestion and sneezing. "Rhino" is from from the Greek word for nose and it is in the nasal passages where the virus likes to live and breed. Coughing, but especially sneezing, spreads cold virus-laden droplets like a shower of confetti. Those who have the misfortune of sharing the same air might end up infected too. Sage advice is to stay home to avoid infecting others.

In fact, the common cold is the number one reason for work and/or school absences. Sore throat, coughing, sneezing and runny nose interfere with concentration making it difficult to focus. Colds interrupt sleep and zap energy making the simplest tasks seem like conquering Mount Everest. Most symptoms only last a week, but coughs may linger for several days. Cold sufferers seeking to feel better faster often look to zinc to stop cold symptoms pronto.

Perhaps you are one of the 62 million Americans with a cold who's tried zinc to zap cold symptoms only to be disappointed that chronic cough and nasal drip persisted despite popping zinc lozenges like breath mints. So what happened? Maybe it was the type of zinc or the dose or the way it was taken. Research suggests that certain forms of zinc delivered within the first day of symptoms can lead to a faster recovery.

Zinc is an essential mineral required for vision, reproduction, and immune function. Whole wheat flour, nuts and red meat are excellent sources of zinc. As a dietary supplement, zinc comes in several forms like zinc gluconate, zinc acetate, zinc citrate, zinc sulfate, zinc carbonate, and zinc picolanate. Not all of these forms of zinc are effective in reducing cold symptoms. The type of zinc as well as how it's delivered, such as oral pill, lozenge or topical gel, influences zinc's cold fighting effectiveness. According to the Cochrane Collaboration of experts, zinc lozenges seem to be effective in adults whereas zinc syrups may be better for children.

The Cochrane review evaluated 15 scientific studies looking at the impact of zinc on zapping cold symptoms and included 1,360 people of all ages and different types of zinc [1]. Zinc, if taken within 24 hours of the first sign of cold symptoms, reduced the duration and severity of the common cold in otherwise healthy adults and children. This was the case if adults used lozenges and children used zinc syrup. For children, one study showed that zinc sulfate syrup in a dose of 15 mg of zinc per day may prevent colds while 30 mg of zinc per day given at the first signs of symptoms may modestly treat a cold [2]. Zinc can be toxic so a pediatrician should be contacted before starting a zinc regimen in children. Also, zinc lozenges pose a choking hazard and are not recommended for kids.

Early cold symptoms may be quelled in adults who use zinc lozenges or gels. Zinc lozenges and nasal gels directly interfere with the rhinovirus' ability to breed in the moist environment of the throat or nose. Zinc gluconate and zinc acetate lozenges or gels have shown the most anti-viral power because they zap the virus at the source. However, these forms of zinc taste nasty so flavorings have been added. But alas, some of these taste boosters may interfere with the virus crushing capacity. Citric acid and tartaric acid are two examples of flavorings to avoid. Also upset stomach and bad taste are common side effects with lozenges [1] [4].
For zinc lozenges to work, the lozenge must completely dissolve in the throat where the virus thrives. The dose required is 13.3 to 23 mg of zinc given every two hours while awake as symptoms persist. This amount of zinc appears to be safe for most adults but should not be used for longer than a week or two. Excessive zinc can be toxic. Too much zinc interferes with copper absorption and may lead to copper deficiency, which can cause anemia and heart problems.

During this cold season you may decide to stock up on zinc lozenges, but before you buy, check the label for flavorings, type of zinc (eg: gluconate or acetate) and zinc amounts. Most lozenges only contain about 5 mg of zinc, well below the suggested amount required to kill the virus, so you may have to consume more lozenges to get the recommended amount. When using zinc nasal gels, do not deeply inhale. Doing so can be painful and there have been some reports of loss of smell.

Zinc can be taken as an oral dietary supplement and may help improve immune function in some. People who took zinc supplements regularly for at least five months suffered from fewer colds and absences [1]. Again, zinc is toxic, so watch the dose and consult with a dietitian or physician for your optimal dose. Several medications, including oral contraceptives, stomach acid reducers, and ACE inhibitors, and nutrients, like calcium and fiber, can reduce oral zinc absorption. Be sure to mention all drugs and supplements to your health care provider.

Zinc, particularly lozenges, if taken in the right dose, at the right time (first 24 hours) and in the right formulation, may reduce cold symptoms by a day or two. Side effects include bad taste and nausea and there is also the potential for toxicity. When it comes to battling the cold bug, zinc may be promising but more research is needed before making a general recommendation.

Selected References:

[1] Singh M, Das RR. Zinc for the common cold. Cochrane Database of Systematic Reviews 2011, Issue 2. Art. No.: CD001364. DOI: 10.1002/14651858.CD001364.pub3.

[2] Kurugol Z et al. The prophylactic and therapeutic effectiveness of zinc sulphate on common cold in children. Acta Paediatr. 2006 Oct;95(10):1175-81.

[4] Stargrove Mitchell Bebell, Treasure Jonathan, McKee Dwight L (2008) Herb, Nutrient, and Drug Interactions, Clinical Implications and Therapeutic Strategies. Mosby